In PR83424 combine's move_deaths puts a REG_DEAD not in the wrong place because dead_or_set_regno_p does not account for CLOBBER insns. This fixes it.
Bootstrapped and tested on powerpc64-linux {-m32,-m64} and on x86_64-linux. Is this okay for trunk? Segher 2017-12-16 Segher Boessenkool <seg...@kernel.crashing.org> PR rtl-optimization/83424 * rtlanal.c (dead_or_set_regno_p): Handle CLOBBER just like SET. gcc/testsuite/ PR rtl-optimization/83424 * gcc.dg/pr83424.c: New testsuite. --- gcc/rtlanal.c | 2 +- gcc/testsuite/gcc.dg/pr83424.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr83424.c diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c index c91f3f1..9f6988b 100644 --- a/gcc/rtlanal.c +++ b/gcc/rtlanal.c @@ -2082,7 +2082,7 @@ dead_or_set_regno_p (const rtx_insn *insn, unsigned int test_regno) if (GET_CODE (pattern) == COND_EXEC) return 0; - if (GET_CODE (pattern) == SET) + if (GET_CODE (pattern) == SET || GET_CODE (pattern) == CLOBBER) return covers_regno_p (SET_DEST (pattern), test_regno); else if (GET_CODE (pattern) == PARALLEL) { diff --git a/gcc/testsuite/gcc.dg/pr83424.c b/gcc/testsuite/gcc.dg/pr83424.c new file mode 100644 index 0000000..5a304f5 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr83424.c @@ -0,0 +1,30 @@ +/* PR rtl-optimization/83424 */ +/* { dg-do run { target int128 } } */ +/* { dg-options "-O -fno-tree-ccp -fno-tree-coalesce-vars" } */ + +typedef unsigned char u8; +typedef unsigned int u32; +typedef unsigned __int128 u128; + +u32 a, c; +u8 b; + +static u128 __attribute__ ((noinline, noclone)) +foo (u128 p) +{ + u8 x = ~b; + p &= c; + x *= -p; + x &= a == 0; + x >>= 1; + return p + x; +} + +int +main (void) +{ + u128 x = foo (0); + if (x != 0) + __builtin_abort (); + return 0; +} -- 1.7.10.4